ppkarwasz commented on issue #3284: URL: https://github.com/apache/logging-log4j2/issues/3284#issuecomment-2541133925
@SweetWuXiaoMei, The NPE seems to be caused by [JMockit](https://jmockit.github.io/index.html). JMockit instruments all the objects involved in your test run (including the "global" Log4j Core objects and their fields). This is the reason why [`Map.computeIfAbsent()`](https://docs.oracle.com/javase/8/docs/api/java/util/Map.html#computeIfAbsent-K-java.util.function.Function-) returns `null` in your test run. Normally this function **never** returns `null` (of course, unless the `mappingFunction` argument returns `null`, which is not the case here). I don't have experience with the JMockit agent, so I cannot tell you if the behavior is expected (I doubt it) or is the result of a bug. You should probably reach out to the JMockit dev team. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: notifications-unsubscr...@logging.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org